LES-based investigation on external heat transfer characteristics of turbine blades for gas turbine (About the effect of turbine blades configuration)

Abstract

Accurate prediction of external heat transfer around a turbine is important in high efficiency gas turbine development. Experimental and computational fluid dynamics studies were performed to investigate the heat transfer characteristics around two types of turbine blades in gas turbines. A four-blade linear cascade in a wind tunnel facility was used in the experiments with inlet Mach number of 0.21, 0.26, and 0.31. Static pressure and heat transfer coefficients around two types of blade models were measured and Large-Eddy Simulations (LES) were conducted to investigate detailed flow phenomenon and heat transfer characteristics. In addition, Reynolds Averaged Navier-Stokes (RANS) simulation also conducted to investigate the potential of reducing analysis time in the turbine design process. Three low-Reynolds number type turbulent models (realizable k-ε, transition k-kl-ω, and transition SST) were used to investigate the validity of the turbulent models used in the RANS simulations, and the analyses results were compared with the experimental results. Boundary layer transition phenomenon and heat transfer characteristics were found to be well predicted by the LES, although the accuracy of the quantitative heat transfer prediction was strongly dependent on the velocity distribution around the turbine blade. RANS simulation reduced the analysis time compared with LES. RANS simulations with transition k-kl-ω and transition SST models approximately predicted the heat transfer distribution with boundary layer transition phenomenon.